1. Field of the Invention
This invention relates to an obstruction inference apparatus for a vehicle for, when the moving vehicle has collided with an obstruction, inferring the type of the obstruction.
2. Description of the Related Art
There have been vehicles equipped with an apparatus for, when the vehicle has hit an obstruction, inferring the type of the obstruction and deploying a secondary collision countermeasure in accordance with that type.
As an apparatus of this kind for deploying a secondary collision countermeasure, an apparatus which operates an air bag located in the vicinity of the hood of the vehicle in accordance with the type of an obstruction is disclosed for example in Japanese Patent Laid-Open Publication No. HEI-8-216826. Another apparatus which operates an air bag located in the vicinity of the hood in accordance with the type of an obstruction is disclosed for example in Japanese Patent Laid-Open Publication No. HEI-11-28994.
FIG. 64 and FIG. 65 are illustrations based on FIG. 6 and FIG. 7 of Japanese Patent Laid-Open Publication No. HEI-8-216826. The names and reference numerals of the constituent elements in these figures have been changed for convenience.
FIG. 64 shows a vehicle 401 equipped with a hood air bag sensor system 400.
This hood air bag sensor system 400 has a bumper sensor 403 on the front bumper 402 of the vehicle 401 and a hood sensor 405 below the hood 404. The hood air bag sensor system 400 also has a control unit 406. The bumper sensor 403 is a sensor for detecting a substantially horizontal load. The hood sensor 405 is a sensor for detecting a substantially vertical load. Only when the bumper sensor 403 and the hood sensor 405 have both detected a load, the control unit 406 infers that an obstruction S11 with which the vehicle has collided is a specified obstruction and outputs a control signal to a hood air bag module 407.
When the vehicle 401 has hit a specified obstruction S11 such as a pedestrian, the hood air bag sensor system 400 detects loads resulting from the collision with the bumper sensor 403 and the hood sensor 405; outputs a control signal from the control unit 406, which receives detection signals from the sensors; and in accordance with this control signal inflates a hood air bag 408 located in the vicinity of the hood 404.
FIG. 65 shows the vehicle 401 having run into an obstruction S12 such as a building.
When only the bumper sensor 403 detects a load, the control unit 406 infers that the obstruction S12 is not a specified obstruction. In this case, the control unit 406 does not output a control signal to the hood air bag module 407, and the hood air bag 408 does not inflate.
Thus the hood air bag sensor system 400 is a system which employs a two-stage detection method wherein a load is detected with the hood sensor 405 after a load is detected with the bumper sensor 403, and on the basis of these two detection signals infers that the obstruction S11 is a specified obstruction and deploys a secondary collision countermeasure.
However, the elapsed time between a load being detected by the bumper sensor 403 and a load being detected by the hood sensor 405 is not fixed. And when this elapsed time is long, the time required for the control unit 406 to infer the type of the obstruction S11 or S12 inevitably becomes long. It is undesirable for it to take time for the type of the obstruction S11 or S12 to be inferred.
Also, even when the obstruction S11 is not a specified obstruction, it can happen that after the bumper sensor 403 detects a load the hood sensor 405 detects a load. In this case the control unit 406 incorrectly infers that the obstruction S11 is a specified obstruction. That is, there is a possibility of an error occurring in the determination of the type of the obstruction S11. The occurrence of this kind of error is undesirable.
FIG. 66 and FIG. 67 are illustrations based on FIG. 4, FIG. 6 and FIG. 7 of Japanese Patent Laid-Open Publication No. HEI-11-28994. In these figures also, the names and reference numerals of constituent elements have for convenience been changed.
FIG. 66 shows a vehicle 501 equipped with a pedestrian protection sensor system 500.
This pedestrian protection sensor system 500 has a load sensor 503 mounted on the front bumper 502 of the vehicle 501 and a vehicle speed sensor 504, and outputs a control signal to a spring-up mechanism 506 from a controller 505, which receives signals from the load sensor 503 and the vehicle speed sensor 504. When the vehicle 501 hits an obstruction S21 at above a certain speed, if the signal from the load sensor 503 is within a fixed range, the controller 505 infers that the obstruction S21 is a specified obstruction and outputs the control signal. In accordance with this control signal, the spring-up mechanism 506 deploys a secondary collision countermeasure by causing the rear end of the hood 507 of the vehicle 501 to spring up. The detailed operation of the controller 505 will be explained on the basis of FIG. 67.
FIG. 67 shows a load sensor output characteristic, with time on the horizontal axis and the sensor output of the load sensor on the vertical axis.
When the front bumper 502 shown in FIG. 66 hits the obstruction S21, the sensor output starts to increase from zero, reaches a peak and then starts to decrease, and again becomes zero. The curve R1 shows a sensor output characteristic of when the vehicle has hit another vehicle or a wall; the curve R2 shows a sensor output characteristic of when the vehicle has hit a tree, a telegraph pole or a sign post; and the curves R3 and R4 show sensor output characteristics of when the vehicle has hit a pedestrian.
Here, Se1 is a first threshold value for determining whether or not the front bumper 502 has hit an obstruction S21. The time at which the sensor output reaches the first threshold value Se1 is Ti1, and time is counted from this time Ti1. When the sensor output increases further and rises above a second threshold value Se2, it is inferred that the obstruction S21 is not a specified obstruction (pedestrian) . When on the other hand the sensor output peaks and starts to decrease without reaching the second threshold value Se2, the time at which it falls back to the first threshold value Se1 is Ti2. When the continuation time Ti0 (Ti0=Ti2xe2x88x92Ti1) from time Ti1 to time Ti2 is within a predetermined fixed time, it is inferred that the obstruction S21 is a specified obstruction (pedestrian).
As is clear from FIG. 67, the curves R3 and R4 are characteristics in which the continuation time Ti0 within the range Se1 to Se2 is relatively short. Besides pedestrians, obstructions having this kind of characteristic include signposts (commonly called pylons) and rubber lane dividers. Even when the obstruction S21 is not a specified obstruction, the controller 105 of the related art described above infers incorrectly that the obstruction S21 is a specified obstruction. That is, there is a possibility of an error occurring in the inference of the type of the obstruction S21. The occurrence of this kind of error is undesirable.
It is therefore a first object of the present invention to provide an obstruction inference apparatus for a vehicle which can infer more accurately the type of an obstruction which the vehicle has hit.
It is a second object of the present invention to provide an obstruction inference apparatus for a vehicle with which it is possible to shorten the time taken to infer the type of an obstruction which the vehicle has hit.
According to a first aspect of the present invention, there is provided an obstruction inference apparatus for a vehicle for inferring the type of an obstruction which the vehicle has hit, the apparatus comprising: a deformable member which deforms in correspondence with an impact force with which the vehicle hits the obstruction; deformation rate detecting means for detecting the deformation rate of this deformable member; timer starting means for starting a timer when the deformation rate detected by this deformation rate detecting means reaches a preset first reference rate in the course of increasing; maximum deformation rate updating means for comparing the deformation rate with a previous maximum deformation rate value detected earlier and setting the larger of the two as a maximum deformation rate; second reference rate generating means for setting as a second reference rate a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset constant smaller than 1.0; elapsed time calculating means for stopping the timer when the deformation rate reaches the second reference rate and obtaining the elapsed time from the timer being started to the timer being stopped; and inference signal generating means for, when the elapsed time is within a preset time range, inferring that the obstruction is a specified obstruction and producing an inference signal.
Here, the deformation rate of the deformable member when the vehicle has hit an obstruction is detected; the elapsed time is obtained from when in the course of increasing this deformation rate reaches a preset first reference rate to when after reaching a maximum deformation rate and decreasing again it reaches a second reference rate; and when this elapsed time is within a predetermined time range it is inferred that the obstruction which the vehicle has hit is a specified obstruction.
Because only a single detecting means, namely the deformation rate detecting means, is used for this inference, the number of detecting means can be reduced. Furthermore, because all that is necessary is for an impact force in one direction to be detected with a single detecting means, the detection time can be shortened.
Also, because just the elapsed time from when the deformation rate reaches a first reference rate to when it reaches a second reference rate is obtained and the type of the obstruction is inferred on the basis of whether or not this elapsed time is with in a predetermined time range, the time needed to infer the type of the obstruction can be made extremely short and the type of the obstruction can be inferred more exactly.
And also, because by the second reference rate generating means a value equivalent to a value obtained by multiplying the maximum deformation rate, which differs according to the type of the obstruction, by a constant smaller than 1.0 is set as the second reference rate, the type of the obstruction can be inferred still more exactly, irrespective of the impact speed at which the obstruction is hit.
The inference signal generating means preferably outputs the inference signal to a secondary collision countermeasure apparatus which deploys a secondary collision countermeasure such as raising the hood of the vehicle or operating an air bag in the hood vicinity.
According to a second aspect of the present invention, there is provided an obstruction inference apparatus for a vehicle for inferring the type of an obstruction which the vehicle has hit, the apparatus comprising: a deformable member which deforms in correspondence with an impact force with which the vehicle hits the obstruction; deformation rate detecting means for detecting the deformation rate of this deformable member; deformation calculating means for obtaining the deformation of the deformable member on the basis of the deformation rate detected by this deformation rate detecting means; maximum deformation rate updating means for comparing the deformation rate with a previous maximum deformation rate value detected earlier and setting the larger of the two as a maximum deformation rate; first reference rate generating means for setting as a first reference rate a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset first rate constant smaller than 1.0; second reference rate generating means for setting as a second reference rate a value equivalent to a value obtained by multiplying the maximum deformation rate by a second rate constant smaller than 1.0 but larger than the first rate constant; first reference deformation generating means for setting as a first reference deformation a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset first deformation constant; second reference deformation generating means for setting as a second reference deformation a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset second deformation constant larger than the first deformation constant; and inference signal generating means for, when the deformation rate is within the range of from the first reference rate to the second reference rate and the deformation is within the range of from the first reference deformation to the second reference deformation, inferring that the obstruction is a specified obstruction and producing an inference signal.
Here, (1) The deformation rate of the deformable member when the vehicle has hit an obstruction is detected; (2) the deformation of the deformable member is obtained on the basis of this deformation rate; (3) the maximum deformation rate, of when the deformation rate reaches its peak, is obtained; (4) on the basis of this maximum deformation rate, a range of from a first reference rate to a second reference rate and a range of from a first reference deformation to a second reference deformation are set; and (5) when the deformation rate is in the range between the first and second reference rates and the deformation is in the range between the first and second reference deformations, it can be inferred that the obstruction which has been hit is a specified obstruction.
Because only a single detecting means, the deformation rate detecting means, is used for this inference, the number of detecting means can be reduced. Furthermore, because all that is necessary is for a deformation rate in one direction to be detected with a single detecting means, the detection time can be shortened.
Also, this apparatus utilizes the fact that, when the deformation rate is in the course of decreasing from its maximum value, the deformation characteristic differs according to the type of the obstruction. Utilizing this characteristic, the type of the obstruction can be inferred on the basis of whether or not two conditions have been met, the first condition being that the deformation rate is in the range between the first and second reference rates and the second condition being that the deformation is in the range between the first and second reference deformations. Accordingly, the time needed to infer the type of the obstruction can be made extremely short and the type of the obstruction can be inferred more exactly.
And also, because values equivalent to values obtained by multiplying the maximum deformation rate, which differs according to the type of the obstruction, with predetermined constants are set as the first and second reference rates and the first and second reference deformations, the type of the obstruction can be inferred still more exactly, irrespective of the impact speed at which the obstruction is hit.
Preferably, the apparatus further has third reference rate generating means for setting as a third reference rate a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset third rate constant smaller than 1.0 but different from the first and second rate constants and third reference deformation generating means for setting as a third reference deformation a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset third deformation constant different from the first and second deformation constants, and is constructed to, when the range of deformation rate and deformation which is both within the range of from the first reference rate to the second reference rate and within the range of from the first reference deformation to the second reference deformation is written as a first reference range, set as a second reference range different from the first reference range a range of deformation rate and deformation which is both within a range based on a combination of the first, second and third reference rates and within a range based on a combination of the first, second and third reference deformations and when the deformation rate and the deformation are within either the first reference range or the second reference range to infer that the obstruction is a specified obstruction and output an inference signal with the inference signal generating means.
The inference signal generating means preferably outputs the inference signal to a secondary collision counter measure apparatus which deploys a secondary collision countermeasure such as raising the hood of the vehicle or operating an air bag in the hood vicinity.
According to a third aspect of the present invention, there is provided an obstruction inference apparatus for a vehicle for inferring the type of an obstruction which the vehicle has hit, the apparatus comprising: a deformable member which deforms in correspondence with an impact force with which the vehicle hits the obstruction; deformation rate detecting means for detecting the deformation rate of this deformable member; deformation detecting means for detecting the deformation of the deformable member; maximum deformation rate updating means for comparing the deformation rate with a previous maximum deformation rate value detected earlier and setting the larger of the two as a maximum deformation rate; reference deformation generating means for setting as a reference deformation a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset deformation constant; inferring means for inferring that the obstruction is a specified obstruction when the deformation has risen above the reference deformation; and inference signal generating means for producing an inference signal on the basis of an inference of the inferring means.
Here the invention utilizes the fact that the ratio of the maximum value of the deformation to the maximum value of the deformation rate, compared with a specified obstruction such as a pedestrian, is smaller with a lighter obstruction. The deformation rate and the deformation of the deformable member when the vehicle has hit an obstruction are detected; the maximum deformation rate, of when the deformation rate reaches its peak, is obtained; a reference deformation is set on the basis of this maximum deformation rate; and when the deformation has risen above this reference deformation, it can be inferred that the obstruction which has been hit is a specified obstruction. Accordingly, a light object is not erroneously inferred to be a specified obstruction. And the type of the obstruction can be inferred more exactly.
The inference signal generating means preferably outputs the inference signal to a secondary collision countermeasure apparatus which deploys a secondary collision countermeasure such as raising the hood of the vehicle or operating an air bag in the hood vicinity.
According to a fourth aspect of the present invention, there is provided an obstruction inference apparatus for a vehicle for inferring the type of an obstruction which the vehicle has hit, the apparatus comprising: a deformable member which deforms in correspondence with an impact force with which the vehicle hits the obstruction; deformation rate detecting means for detecting the deformation rate of this deformable member; deformation detecting means for detecting the deformation of the deformable member; maximum deformation rate updating means for comparing the deformation rate with a previous maximum deformation rate value detected earlier and setting the larger of the two as a maximum deformation rate; reference rate generating means for setting as a reference rate a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset rate constant smaller than 1.0; first reference deformation generating means for setting as a first reference deformation a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset first deformation constant; second reference deformation generating means for setting as a second reference deformation a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset second deformation constant larger than the first deformation constant; inferring means for inferring that the obstruction is a specified obstruction when within a preset inference time from when the vehicle hit the obstruction the deformation rate is smaller than the reference rate and the deformation is in the range of from the first reference deformation to the second reference deformation; and inference signal generating means for producing an inference signal on the basis an inference of this inferring means.
Here the invention utilizes the fact that the ratio of the maximum value of the deformation to the maximum value of the deformation rate, compared with a specified obstruction such as a pedestrian, is smaller with a lighter obstruction. The deformation rate and the deformation of the deformable member when the vehicle has hit an obstruction are detected; the maximum deformation rate, of when the deformation rate reaches its peak, is obtained; a reference rate and a range of from a first reference deformation to a second reference deformation are set on the basis of this maximum deformation rate; and when within a preset inference time from when the vehicle hits the obstruction the deformation rate is smaller than the reference rate and the deformation is in the range of from the first reference deformation to the second reference deformation, it can be inferred that the obstruction which has been hit is a specified obstruction. Accordingly, a light object is not erroneously inferred to be a specified obstruction.
When the vehicle hits an obstruction with a low center of gravity, such as a small animal caught by the underside of the vehicle, the deformable member deforms so as to be pulled to the lower side of the vehicle and rearward. The time from the time of impact to when the deformation rate of the deformable member reaches zero after peaking in this case is relatively long compared to when the obstruction is a specified obstruction such as a pedestrian.
In the fourth aspect of the invention, to utilize this characteristic, it is inferred that the obstruction which has been hit is a specified obstruction when within an inference time the deformation rate and the deformation satisfy the predetermined conditions set forth above. Consequently, an obstruction with a low center of gravity such as a small animal caught by the underside of the vehicle is not erroneously inferred to be a specified obstruction.
In this kind of way, the type of an obstruction can be inferred more exactly.
The inference signal generating means preferably outputs the inference signal to a secondary collision countermeasure apparatus which deploys a secondary collision countermeasure such as raising the hood of the vehicle or operating an air bag in the hood vicinity.
According to a fifth aspect of the present invention, there is provided an obstruction inference apparatus for a vehicle for inferring the type of an obstruction which the vehicle has hit, having: a deformable member which deforms in correspondence with an impact force with which the vehicle hits the obstruction; deformation rate detecting means for detecting the deformation rate of this deformable member; deformation detecting means for detecting the deformation of the deformable member; maximum deformation rate updating means for comparing the deformation rate with a previous maximum deformation rate value detected earlier and setting the larger of the two as a maximum deformation rate; first reference rate generating means for setting as a first reference rate a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset first rate constant smaller than 1.0; second reference rate generating means for setting as a second reference rate a value equivalent to a value obtained by multiplying the maximum deformation rate by a second rate constant smaller than 1.0 but larger than the first rate constant; first reference deformation generating means for setting as a first reference deformation a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset first deformation constant; second reference deformation generating means for setting as a second reference deformation a value equivalent to a value obtained by multiplying the maximum deformation rate by a preset second deformation constant larger than the first deformation constant; inferring means for inferring that the obstruction is a specified obstruction when the deformation rate is in the range of from the first reference rate to the second reference rate and the deformation is in the range of from the first reference deformation to the second reference deformation; deformation rate determining means for determining that the deformation rate has risen above a preset third reference rate different from the first and second reference rates; deformation determining means for determining that the deformation has risen above a preset third reference deformation different from the first and second reference deformations; additional inferring means for additionally inferring that the obstruction is a specified obstruction when receiving an inference signal from the inferring means, a determination signal from the deformation rate determining means and a determination signal from the deformation determining means; and inference signal generating means for producing an inference signal on the basis of an additional inference of this additional inferring means.
Here, the deformation rate and the deformation of the deformable member when the vehicle hits an obstruction are detected; the maximum deformation rate, of when the deformation rate of the deformable member reaches its peak, is obtained; on the basis of this maximum deformation rate a range of from a first reference rate to a second reference rate and a range of from a first reference deformation to a second reference deformation are set; and also, a third reference rate and a third reference deformation not based on the maximum deformation rate are set.
Accordingly, it can be inferred that the obstruction which has been hit is a specified obstruction when the following four conditions are satisfied: (1) a first condition of the deformation rate being in the range between the first and second reference rates; (2) a second condition of the deformation being in the range between the first and second reference deformations; (3) a third condition of the deformation rate exceeding the third reference rate; and (4) a fourth condition of the deformation exceeding the third reference deformation.
Consequently, a light object is not erroneously inferred to be a specified obstruction. And moreover an obstruction with a low center of gravity, such as a small animal caught by the underside of the vehicle, is not erroneously inferred to be a specified obstruction. Thus the type of the obstruction can be inferred more exactly.
The inference signal generating means preferably outputs the inference signal to a secondary collision countermeasure apparatus which deploys a secondary collision countermeasure such as raising the hood of the vehicle or operating an air bag in the hood vicinity.